lib: Return an RDResolution even if image is too small to analyze
lib: Return an RDResolution even if image is too small to analyze

As long as this is not NULL we allocate it and provide the base
size as the first element. For clients using only resdetect_file,
this is the primary way to obtain the width and height.

0x09/resdet,0x09/resdet,0x09/resdet,0x09/resdet